The disclosed apparatus relates to Ser. No. 844,476 filed on even date herewith and entitled A Modular High Speed Printing System as well as Ser. No. 844,475 also filed on even date and entitled Method and Apparatus For Monitoring the Passage of Articles Through A Modular Processing System. The referenced applications are commonly assigned and the subject matter of each of them is hereby incorporated by reference.
The patent application entitled A Modular High Speed Printing System sets forth a modular document printing system which comprises a document feeder module coupled to one or more document printing modules and a document receiver module. The document printing modules include printheads which can print sequential numeric information, constant numeric information and alphanumeric information on documents which are conveyed through the system. The printing system disclosed therein also includes a plurality of document sensors for sensing the feeding of documents into the processing system as well as the entry and exit of documents from each printing module. The modular high speed printing system can be employed to print bank documents such as checks and deposit slips while also having many other applications in the high speed printing of documents. It can be appreciated that the formats of these documents can vary widely and that a modular printing system must possess a high degree of flexibility in order to be effectively and advantageously employed. It has been found that in a large number of applications it is necessary for the documents to include one or more apertures primarily along one edge to permit, for example, the insertion of the documents into ring binders for storage. Also, many times documents are bound within a pad but will include apertures for sorting or other purposes.
The prior art printing systems for preparing such documents primarily employ optical transducers for sensing the presence or absence of a document. A problem arises when the optical transducer recognizes the leading boundary of an aperture within a document as the end of the document and the trailing boundary of the same aperture as the leading edge of a second document. Many of the prior art devices were found to be unsuitable for printing on such documents because they could not accommodate the presence of apertures in the documents.
The instant apparatus can be incorporated into each of the printing or processing modules wherever there is an optical type sensor to inhibit the indication of a discontinuity in a document merely because that document includes one or more apertures. While having the ability to accommodate apertures of a specified maximum size anywhere within the document, the hole mask circuit also recognizes the presence of damaged or invalid documents while being able to accommodate the spacing between successive documents.